Cerebral microbleeds are a risk factor for warfarin-related intracerebral hemorrhage

Background: Cerebral microbleeds are known to be indicative of bleeding-prone microangiopathy and may predict incident intracerebral hemorrhage (ICH). In this study, we investigated whether microbleeds are associated with the incidence of warfarin-related ICH. Methods: Twenty-four patients with ICH while on outpatient treatment with warfarin were selected from a consecutive cohort. Control, warfarin-using subjects with no history of ICH were randomly selected during the same time period (n = 48). We compared demographic factors, vascular risk factors, laboratory findings, and radiologic findings including microbleeds between the groups. Result: There were more cases of patients with microbleeds in the ICH than control group (79.2% vs 22.9%: p < 0.001), and the number of microbleeds was much higher for the ICH group (9.0 +/- 26.8 vs 0.5 +/- 1.03: p +/- 0.001). Moreover, the number of microbleeds was significantly correlated with the presence of warfarin-related ICH (r = 0.299; p = 0.001). Conditional logistic regression analysis showed that increased prothrombin time and the presence of microbleeds were independently related to the incidence of warfarin-related ICH (microbleeds: adjusted OR, 83.12). Conclusion: This study suggests that underlying microbleeds are independently associated with an incidence of warfarin-related intracerebral hemorrhage. Future research should focus on elucidating the risks and benefits of warfarin medication in patients with microbleeds. Neurology (R) 2009; 72: 171-176